VIENNA: The head of the Organization of Petroleum Exporting Countries warned Thursday that oil prices would see an "unlimited" increase in the case of a military conflict involving Iran, because the group's members would be unable to make up the lost production.

Iran, the second-largest producing country in OPEC, after Saudi Arabia, produces about 4 million barrels of oil a day out of the daily worldwide production of close to 87 million barrels. The country has been locked in a lengthy dispute with Western countries over its nuclear ambitions.

In recent weeks, the price of oil has risen higher on speculation that Israel could be preparing to attack Iranian nuclear facilities. The saber-rattling intensified this week with missile tests by Iran. That has further shaken oil markets because of concerns that any conflict with Iran could disrupt oil shipments from the Gulf region.

"The prices would go unlimited," Badri said during the interview, referring to the effect of a military conflict. "I can't give you a number."